Funding for this research was provided by:
National Natural Science Foundation of China (61673141, 61571168)
Alexander von Humboldt Foundation of Germany
Fok Ying Tung Education Foundation of China (151004)
Article History
Received: 19 February 2019
Revised: 24 June 2019
Accepted: 24 June 2019
First Online: 12 July 2019
Compliance with Ethical Standards
:
: The authors claim that there are no potential conflicts of interest. In addition, this submission has been approved by all co-authors.